Leukocyte depletion improves early postischemic ventricular performance in neonatal models of global myocardial ischemia. However, the rate of leukocyte reaccumulation after cardiopulmonary bypass and its subsequent impact on myocardial function is not known. This laboratory study examined the effect of leukocyte depletion on myocardial performance during the initial 6-hour period after bypass in an in situ, in vivo porcine model of neonatal cardiac surgery. Fifteen 3- to 5-day-old piglets (eight control and seven leukocyte depleted animals) were instrumented by placement of left ventricular short-axis sonomicrometry crystals and an intraventricular micromanometer catheter. Mechanical leukocyte depletion was achieved with Pall RC100 filters (Pall Biomedical, Inc., Fajardo, Puerto Rico) in the cardiopulmonary bypass circuit. Neonatal hearts were subjected to 90 minutes of hypothermic ischemia after a single dose of cold crystalloid cardioplegia. Two control animals died after the operation and were excluded from data analysis. Leukocyte filtration reduced the granulocyte count during initial myocardial reperfusion to 0.8% of control values. However, circulating granulocyte counts increased in leukocyte depleted animals throughout the postoperative period, reaching 68% of control values by 6 hours. Despite this rapid return of circulating granulocytes, animals subjected to leukocyte depletion had significantly better preservation of left ventricular performance (measured by preload recruitable stroke work, p ≤ 0.02), left ventricular systolic function (measured by end-systolic pressure-volume relationship, p ≤ 0.05), and ventricular compliance (p ≤ 0.04) during the experiment. These changes in ventricular function were associated with a significant increase in left ventricular water content (p ≤ 0.02) and tissue myeloperoxidase activity (p ≤ 0.005) in control animals compared with leukocyte depleted animals. This study demonstrates that leukocyte depletion during initial reperfusion results in sustained improvement in postischemic left ventricular function despite the rapid return of granulocytes to the circulation.
Neutrophil accumulation and activation within the myocardium during ischemia and reperfusion has been shown to play a prominent role in the development of myocardial stunning and infarction.To determine if a simple inhibitor of neutrophil adhesion could reduce myocardial infarct size, we administered NPC 15669 (a new antiinflammatory agent that inhibits neutrophil adhesion) to 12 pigs (6 controls, 6 NPC-treated) in a porcine model of ischemia and reperfusion injury.Each animal received a continuous infusion of either NPC (10 mg/kg intravenous bolus followed by 6 mgkg-' * h-' intravenous infusion) or an equal volume of normal saline solution during 1 hour of left anterior descending artery occlusion and 2 hours of reperfusion.There were no eutrophil accumulation and activation within myo-N cardium has been shown to play a prominent role in extension of myocardial infarction [ 1-61.Activated neutrophils release numerous cytotoxic metabolites, including oxygen free radicals and proteolytic enzymes that are highly damaging to tissue [7, 81.Recent work indicates that activated neutrophils have increased adhesiveness to endothelial cells after modulation of their cell surface adhesion molecules [9].Most notable among these adhesion molecules is a neutrophil membrane glycoprotein known as the Mac-1, or CDllb/CD18, adhesion molecule.Several studies have demonstrated that inhibition of neutrophil adherence by monoclonal antibodies directed against the Mac-1 protein attenuates myocardial infarction and stunning [3, 5, lo].Such antibodies, although important as research tools, are too costly and in limited supply to be useful as therapeutic agents.Recently, a new class of antiinflammatory agents that inhibit neutrophil recruitment was introduced into clinical trials for treatment of several inflammatory diseases.These "leumedins" are amino acids that have been shown in several animal models to reduce neutrophil recruitment and infiltration into areas of inflammation [ll, 121.One of the principal activities of leumedins appears to be inhibition of up-regulation of the Mac-1 adhesion molecule.In this present study, we report the use of the leumedin
The objective of this work was to determine whether normothermic global cardiac ischemia in a porcine model was associated with a change in the density (Bmax) of voltage-dependent calcium channels in myocardial sarcolemmal membranes. Pigs were anesthetized, a thoracotomy was performed, and samples were taken of the left and right ventricles from control and ischemic hearts. Dihydropyridine-binding sites were quantified using [(3) H]isradipine, and 5 prime-nucleotidase activity was measured by the liberation of inorganic phosphate from adenosine monophosphate. B (max) and dissociation constants and 5 prime-nucleotidase activity for control and ischemic tissues, respectively, were compared by using Student's t-test for unpaired samples. After normothermic global ischemia, the Bmax of [(3) H]isradipine binding increased in the left ventricle by 81% (299% +/- 1.7% to 540% +/- 11% fmoles/mg, P < 0.01) and in the right ventricle by 33% (387% +/- 9.9% to 515% +/- 38% fmoles/mg, P < 0.01) compared with control. 5 prime-nucleotidase activity increased by 48% in the left ventricle and by 96% in the right ventricle (p < 0.05). Fifteen minutes of normothermic ischemia in the pig is associated with marked sarcolemmal abnormalities, including increases in specific dihydropyridine binding and 5 prime-nucleotidase activity, which reflect global changes in membrane function, which might contribute to the increase in myoplasmic calcium during ischemia. (Anesth Analg 1997;84:972-5)
We hypothesized that measurement of a specific product from reaction of N,N'-dimethylthiourea (Me2TU) and H2O2 would provide a good indication of the H2O2 scavenging and protection seen after addition of Me2TU to biological systems. We found that addition of H2O2 to Me2TU yielded a single stable product, Me2TU dioxide. Me2TU dioxide formation correlated with Me2TU consumption as a function of added H2O2 concentration and was prevented by simultaneous addition of catalase (but not boiled catalase), superoxide dismutase, dimethyl sulfoxide, mannitol, or sodium benzoate. Me2TU dioxide formation, Me2TU consumption, and H2O2 concentration increases occurred in mixtures containing phorbol 12-myristate 13-acetate (PMA) and normal human neutrophils but not in mixtures containing PMA and neutrophils from patients with chronic granulomatous disease or in mixtures containing PMA and normal neutrophils and catalase. Me2TU dioxide formation also occurred in isolated rat lungs perfused with Me2TU and H2O2 but not in lungs perfused with Me2TU and elastase, histamine, or oleic acid. In contrast, Me2TU dioxide formation did not occur after exposure of Me2TU to 60Co-generated hydroxyl radical or hypochlorous acid in the presence of catalase. The results indicate that reaction of Me2TU with H2O2 selectively forms Me2TU dioxide and that measuring Me2TU dioxide formation from Me2TU may be useful for assessing the presence and significance of H2O2 in biological systems.
